Phobias

Have you ever felt the kind of fear that sends shockwaves through your entire body? You might tremble uncontrollably and even feel ill. How about a kind of fear that prevents you from living a normal, healthy lifestyle?

Chloe Tse never forgot when she was five years old and got chased by a dog. Living in Sha Tin at the time, the 24-year old says there were always dogs running around. 'My natural reaction was to run, but looking back now, I think it was probably just trying to be friendly by chasing me,' Tse says. 'I just didn't want the dog to touch me. I find them dirty.'

When humans were concerned about tackling wild beasts just to get through the day, they didn't have to think about living 'ideal' lives. However, experts say that in the modern world our brains are overloaded with anxieties that we can't always cope with, and our internal mechanisms are struggling to catch up with a constant flow of visual and aural information.

What makes you afraid? Does your heart beat faster and do your hands get sweaty when you're alone in the dark? We all get scared sometimes and there's very little we can do about it. Some people even enjoy being a little scared and pay money to watch horror movies or go on roller-coaster rides. Let's face a few fears ...

A panic attack means the sympathetic nervous system has been activated for the fight or flight mechanism. This was useful when humans were under attack - from a wild beast, for example. It responds dramatically to the concept of danger.

The Hong Kong Mood Disorders Centre offers two phobia-related services. If you need to be seen immediately, staff can refer you to a private doctor trained to deal with anxiety disorders. If you're prepared to go on a waiting list, the centre has its own clinical psychologists, who can arrange private weekly therapy sessions for a fee.

Enormous objects such as planets and stars create a lot of gravity because they have a lot of matter occupying a relatively small space. The sun creates a lot of gravity and can therefore keep us in orbit. The same thing applies to Earth and its moon.